Signaling and routing protocools for an integrated cellular and relaying system

ABSTRACT

The present invention provides signaling protocols that enable an integrated cellular relaying system to support a call for a wireless terminal. In embodiments of the invention, the wireless terminal is redirected to a relaying path corresponding to at least one relaying station. A relaying station communicates with the wireless terminal and with other relaying stations. In addition, one of the relaying stations (that is configured in the relaying path) completes the relaying path by communicating with a base transceiver station.

FIELD OF THE INVENTION

[0001] This invention relates to utilizing relaying stations to completecalls in a cellular radio system.

BACKGROUND OF THE INVENTION

[0002] The cellular radio concept was introduced for wirelesscommunications to address the scarcity of frequency spectrum Thecellular radio concept is predicated on the sub-dividing of ageographical area into cells. Each cell is served by a base transceiverstation (BTS). The frequency spectrum is reused in order to increase thecall capacity of a wireless system. However, in order to avoid signalinterference resulting from frequency reuse, cell boundaries prevent thefrequency spectrum (corresponding to channels) that is assigned to acell from being accessible to mobile hosts (wireless terminals) in cellsin close proximity. Thus, a mobile host (MH) in a cell of a wirelesssystem can use only a cellular bandwidth (CBW) of a BTS that is servingthe cell.

[0003] When a call request occurs at a BTS that does not have sufficientCBW to support the call, the call request is rejected even thoughsufficient CBW is available at other BTS's (associated with other cells)of the wireless system. With spread spectrum wireless technology (suchas code division multiple access (CDMA)), the frequency reuse factor isapproximately 1, i.e., each BTS utilizes essentially the same frequencyspectrum. However, each BTS is distinguished from other BTS's by digitalencoding. Rather than being assigned a distinct portion of frequencyspectrum, a mobile host is assigned a distinguishable digital channel.In such a case CBW is not associated with a distinct portion offrequency spectrum but with a digital channel. Not being able to accessCBW of another BTS in other cells (which may not be utilizing all itsCBW) limits the call capacity of a wireless system.

[0004]FIG. 1 shows an architecture of a wireless system 100 according tothe prior art. Wireless system 100 comprises a packet switching center(PSC) 151, a BTS 107, a BTS 109, and a BTS 111. PSC 151 may beimplemented as a base station controller (BSC) or a radio networkcontroller (RNC). (A PSC may be referred as a “wireless controller.”)PSC 151 maintains and provides current CBW for BTS 107, BSC 109, and BSC111 for supporting calls for MH 113 and MH 115 through control lines152, 154, and 156, respectively. PSC 151 instructs BTS 107, 109, and 111to assign CBW to a call for MH 113 and 115 through control lines 152,154, and 156.

[0005] In FIG. 1, MH 115 is currently being served by BTS 109 in a cell103. At the instant of time, BTS 109 does not have spare CBW in order toserve other mobile hosts (wireless terminals). However, MH 113, which isin cell 103, requests that BTS 109 support a call by assigning CBW. Thecall may correspond to a call setup (originated by MH 115 or terminatedat MH 115) or to a handoff in which MH 113 was previously served byanother BTS in another cell (e.g. BTS 107 in cell 101) and has movedinto cell 103. Even though BTS 107 or BTS 111 may have spare capacity(i.e., CBW), MH 113 is unable to benefit from resources of BTS's incorresponding cells in which MH 113 is not located. Thus, a call willfail in such a case.

SUMMARY OF THE INVENTION

[0006] The present invention provides signaling protocols that enable anintegrated cellular relaying system to support a call for a wirelessterminal. In embodiments of the invention, the wireless terminal isredirected to a relaying path corresponding to at least one relayingstation. A relaying station communicates with the wireless terminal andwith other relaying stations. In addition, one of the relaying stations(that is configured in the relaying path) completes the relaying path bycommunicating with a base transceiver station.

[0007] The first embodiment of the invention provides a signalingprotocol for relaying a call through at least one ad hoc relayingstation (ARS) that utilizes a packet switching center. The packetswitching center maintains bandwidth information about ad hoc relayingstations and base transceiver stations and determines a relaying pathaccording to a criterion such as a cost that is associated with therelaying path. The packet switching center instructs a plurality of basetransceiver stations to initiate the establishment of the relaying path.Consequently, the plurality of base transceiver stations configureassociated ad hoc relaying stations to configure the relaying path. Thewireless terminal utilizes the relaying path to complete the call to oneof the base transceiver stations.

[0008] The second embodiment of the invention provides a signalingprotocol for relaying a call through at least one ad hoc relayingstation in which a relaying path is determined by one of the ad hocrelaying stations. The ad hoc relaying stations maintain topological andbandwidth information about other ad hoc relaying stations and receivebandwidth information about base transceiver stations through messaging.

[0009] The third embodiment of the invention provides a signalingprotocol for relaying a call through at least one ad hoc relayingstation in which a plurality of relaying paths are established. The adhoc relaying station need not maintain bandwidth information about otherad hoc relaying stations and base transceiver stations. One relayingpath is selected to support the call in accordance with a criterion. Theother relaying paths are torn down by the corresponding ad hoc relayingstations.

[0010] In other embodiments of the invention, computer-executableinstructions or control logic for implementing the disclosed methods arestored on computer-readable media or implemented with hardware modules.

[0011] Other features and advantages of the invention will becomeapparent with reference to the following detailed description and thefigures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] A more complete understanding of the present invention and theadvantages thereof may be acquired by referring to the followingdescription in consideration of the accompanying drawings, in which likereference numbers indicate like features and wherein:

[0013]FIG. 1 shows an architecture of a wireless system according to theprior art;

[0014]FIG. 2 shows an architecture of an integrated cellular andrelaying (iCAR) system utilizing primary relaying, in accordance to anembodiment of the invention;

[0015]FIG. 3 shows an architecture of an integrated cellular andrelaying (iCAR) system utilizing secondary relaying, in accordance to anembodiment of the invention;

[0016]FIG. 4 shows a packet switching center (PSC)-assisted signalprotocol scenario utilizing primary relaying according to an embodimentof the invention;

[0017]FIG. 5 shows apparatus of a packet switching center (PSC)according to an embodiment of the invention;

[0018]FIG. 6 shows apparatus for an ad hoc relaying station (ARS)according to an embodiment of the invention;

[0019]FIG. 7 shows apparatus for a mobile host (MH) according to anembodiment of the invention;

[0020]FIG. 8 shows apparatus of a base transceiver station (BTS)according to an embodiment of the invention;

[0021]FIG. 9 shows a PSC-assisted signaling protocol scenario utilizingsecondary relaying according to an embodiment of the invention;

[0022]FIG. 10 shows a link-state based distributed signaling protocolscenario utilizing primary relaying according to an embodiment of theinvention;

[0023]FIG. 11 shows apparatus of an ad hoc relaying station (ARS) thatsupports the protocol scenarios in FIGS. 10 and 12;

[0024]FIG. 12 shows a link-state based distributed signaling protocolscenario utilizing secondary relaying according to an embodiment of theinvention;

[0025]FIG. 13 shows a distributed signaling protocol scenario utilizingprimary relaying according to an embodiment of the invention;

[0026]FIG. 14 shows apparatus of an ad hoc relaying station (ARS) thatsupports the protocol scenarios shown FIGS. 13 and 15; and

[0027]FIG. 15 shows a distributed signaling protocol scenario utilizingsecondary relaying according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0028] In the following description of the various embodiments,reference is made to the accompanying drawings which form a part hereof,and in which is shown by way of illustration various embodiments inwhich the invention may be practiced. It is to be understood that otherembodiments may be utilized and structural and functional modificationsmay be made without departing from the scope of the present invention.

[0029]FIG. 2 shows an architecture of an integrated cellular and ad hocrelaying (iCAR) system 200 according to an embodiment of the invention.In order to increase the call capacity of wireless system 200, ad hocrelaying stations (ARS) 201, 203, 205, 207, and 209 are integrated withthe operation of base transceiver stations (BTS) 107, 109, and 111 andPSC 151. A BTS comprises a receiver and a transmitter in order tocommunicate with a mobile host over a wireless channel. (The terms“mobile host” and “wireless terminal” are used interchangeably. A mobilehost or a wireless terminal can provide voice, data, and multimediaservices.) The BTS utilizes frequency spectrum that is allocated forcellular radio operation. Also, the term “ad hoc relaying station”clarifies that a relaying station can be placed geographically anywherein the wireless system. MH 115 is served by BTS 109 utilizing cellularfrequency spectrum and corresponding to a cellular bandwidth (CBW). Withother embodiments of the present invention that utilize spread spectrumtechnology (e.g. code division multiple access (CDMA)), CBW correspondsto a digital channel. ( The terms “channel” and “cellular bandwidth” areused interchangeably.)

[0030] As in FIG. 1, MH 113 cannot be served by BTS 109 because BTS 109has used all of its assigned CBW. BTS 107 does have CBW that can beassigned to a call for MH 113; however, MH 113 cannot be directly servedby BTS 107 because MH 113 is located in cell 103 rather than in cell101, which is the serving area of BTS 107.

[0031] In order to support a communication path between MH 113 and BTS107, iCAR system 200 configures ARS 201 and ARS 203 in a relaying path.ARS 201, 203, 205, 207, and 209 have two radio interfaces: a cellularinterface (C-interface) for communicating with a BTS and arelaying-interface (R-interface) for communicating with a MH or anotherARS. In the exemplary embodiments, the C-interface operates atapproximately 1900 MHz, corresponding to the personal communicationssystem (PCS) frequency spectrum, while the R-interface operates atapproximately 2.4 GHz, corresponding to unlicensed Industrial ScientificMedical (ISM) frequency spectrum (However, alternative embodiments canutilize other frequency spectra, in which a first frequency spectrum isassociated with the C-interface and a second frequency spectrum isassociated with the R-interface.) In the exemplary embodiments, thetransmission range of ARS 201, 203, 205, 207, and 209 is typicallyshorter over the R-interface than over the C-interface. Also, thetransmission capability of the ARS's is typically larger than thetransmission capability of the MH's.

[0032] ARS 201, 203, 205, 207, and 211 can support the followingfunctionality, depending upon the configuration of a call:

[0033] Proxy ARS: supports a point of contact with an MH (e.g. ARS 201in FIG. 2)

[0034] Gateway ARS: supports a point of contact with the BTS that servesthe call (e.g. ARS 203 in FIG. 2). A gateway ARS utilizes both theR-interface and the C-interface in supporting a call.

[0035] Intermediate ARS: supports a point of contact between the proxyARS and the gateway ARS.

[0036] Also, in the exemplary embodiments, a BTS instructs an ARS on theC-interface in order to configure the ARS for a call as will bediscussed with the signaling protocol scenarios shown in FIGS. 4, 9, 10,12, 13, and 15.

[0037] In the exemplary embodiments, MH 113 and MH 115 support both theR-interface and the C-interface. The R-interface is utilized by themobile host to communicate through an ARS to a BTS. The mobile hosttransmits signaling messages to an ARS (as shown in FIGS. 4, 9, 10, 12,13, and 15) using the R-interface. Also, the mobile host utilizes theR-interface to transport user information (e.g. voice or data) to an ARSwhen a relaying path has been established. The C-interface is utilizedby the mobile host when the mobile host communicates directly with aBTS. The mobile host also utilizes the C-interface when sendingsignaling messages or user data (e.g. voice or data) directly to a BTS.Also, the ARS utilizes the C-interface when sending signaling messagesor sending user information (that the ARS is relaying) to a BTS.

[0038] In FIG. 2, MH 113 is served by BTS 107 through the relaying path:R-link 202, ARS 201, R-link 204, ARS 203, and C-link 206. Each R-linkutilizes ISM frequency spectrum with an associated relaying bandwidth(RBW). Each C-link utilizes cellular frequency spectrum with anassociated CBW. ARS 201 serves as a proxy ARS and ARS 203 serves as agateway ARS.

[0039]FIG. 3 shows an architecture of an iCAR system 300 utilizingsecondary relaying. In FIG. 3, BTS 109 has insufficient CBW to serve MH113. However, unlike with FIG. 2, MH 113 is not in close proximity toconnect to ARS 201. (In FIG. 3, ARS 201 is not configured as in iCAR200.) In such a case, another mobile host that is currently being servedby BTS 109 is redirected to a secondary relaying path through at leastone ARS to a BTS that serves a cell in which the mobile host is notlocated. MH 115 is instructed to connect to BTS 111, termed a foreignBTS (F_BTS), through R-link 302, ARS 207, R-link 304, ARS 209, andC-link 306. The vacated CBW at BTS 109, termed the home BTS (H_BTS),that was previously assigned to MH 115 is reassigned to MH 113.

[0040] In the embodiment, call processing utilizing secondary relayingis executed if primary relaying is unsuccessful. (However, otherembodiments of the invention may utilize secondary relaying withoutpreviously attempting primary relaying.) Both primary relaying andsecondary relaying are applicable to different wireless technologies,including analog technologies, time division multiple accesstechnologies, and code division multiple access technologies. Moreover,both primary relaying and secondary relaying support calls correspondingto voice services, data services, and multimedia services.

[0041] Both primary and secondary relaying can be utilized duringsetting up a call (either a mobile host originating a call or a callterminating to a mobile host) and during handing off a mobile host asthe mobile host moves into a serving region of another BTS. In someembodiments of the invention, a mobile host is notified by a basetransceiver station to initiate either primary or secondary relayingwhen the mobile host is being called (i.e. a call terminating to themobile host) or when the mobile host is being handed off during a call.Moreover the call capacity of iCAR system 200 and iCAR system 300 can beincreased by balancing (distributing) calls to BTS's that have CBW whenother BTS's do not have sufficient CBW to serve mobile hosts withincorresponding cells. In accordance with the signaling protocolsdisclosed herein, other embodiments of the invention can utilize primaryand secondary relaying in order to ameliorate a shortage of BTSresources (e.g. processing capacity) other than the assigned frequencyspectrum.

[0042] In the signaling protocol scenarios shown in FIGS. 4, 9, 10, 12,13, and 15 signaling messages utilize the C-interface to a BTS on acontrol channel even though the BTS does not have sufficient CBW tosupport user traffic (e.g. voice and user data). In wireless systems,signaling messages typically can be sent over the control channel eventhough dedicated channels that transport user traffic are congested.

[0043]FIG. 4 shows a packet switching center (PSC)-assisted signalprotocol scenario utilizing primary relaying according to a firstembodiment of the invention. The signal protocol scenario of FIG. 4corresponds to the architecture that is shown in FIG. 2. MH 113 requestsfor a call by sending CBW_REQ 401 to BTS 109. (BTS 109 serves as a homeBTS (H_BTS) for the call). BTS 109 queries PSC 151 for spectrumassignment by sending CBW_REQ 403. In this protocol scenario, PSC 151determines that BTS 109 does not have adequate CBW to assign to MH 113,so PSC 151 returns CBW_NAK 405 to BTS 109. BTS 109 sends CBW_NAK 407 toMH 113, indicating that a call cannot be supported because ofinsufficient CBW.

[0044] BTS 109 starts timer T1 408 after sending CBW_NAK 407. If timer408 has not expired, BTS 109 processes a response from an ARS (e.g. ARS201 returning P_RELAY_REQ 411). The value of timer 408 is typicallylimited by the maximum delay budget that is allowed for primaryrelaying. (In subsequent discussions of signaling protocol scenarios inFIGS. 9, 10, 12, 13, and 15, the consideration of timers is not shown.However, one skilled in the art appreciates that the inclusion of timersmay resolve any abnormalities that may occur with processing a call.)

[0045] Upon receiving CBW_NAK 407, MH 113 queries whether any ARS's(e.g. ARS 201) can support the call by broadcasting P_RELAY_REQ 409 overthe R-interface with a sequence number that is associated with MH 113.(FIG. 2 only shows one ARS in close proximity to the location of MH 113;however the present invention supports a plurality of ARS's.) ARS 201processes message 409 and sends P_RELAY_REQ to BTS 109 over the C-linkwith the sequence number. The responses (e.g. response 411) areforwarded by BTS 109 to PSC 151 using P_RELAY_REQ 413. The sequencenumber is included in message 413 so that MH 113 can be subsequentlyidentified. In the embodiment, BTS 109 starts a timer after sendingCBW_NAK 407. BTS 109 processes a P_RELAY_REQ message (e.g. message 411)from an ARS if the message is received before the timer expires.

[0046] PSC 151 utilizes information about the system topology andbandwidth (both RBW and CBW) to determine the shortest relaying pathfrom one of the responding ARS's to a non-congested BTS. In theembodiment, PSC 151 maintains bandwidth information about each BTS andARS within the serving region of the PSC (i.e., cells 101, 103, and105). PSC 151 determines the shortest relaying path by determining theminimum distance for all possible paths. In the embodiment, PSC 151determines the path with the least number of hops, in which a hop isbetween adjacent nodes (either an ARS or BTS) of the path However, otherembodiments may utilize other criteria, including determining a relayingpath with the greatest available bandwidth. For example, with such anembodiment the available RBW of each ARS along a possible path isdetermined. A corresponding reciprocal (1/RBW) is calculated and the sumof the reciprocals corresponding to the possible path is determined. Thepath that is associated with the smallest sum with respect to otherpossible paths is deemed as having the greatest available bandwidth.

[0047] If PSC 151 determines that a relaying path is available, PSC 151will send P_RELAY_ACK 415 to BTS 109 and P_RELAY_ACK 417 to BTS 107(which functions as a foreign BTS in this call scenario). P_RELAY_ACK415 and 417 contains the complete routing information of the relayingpath (i.e., the identification of all ARS's and the destination BTSassociated with the path as well as the sequence number). BTS 107reserves CBW that is needed for the connection with ARS 203 (whichfunctions as a gateway ARS). BTS 109 and BTS 107 consequently multicastP_RELAY_ROUTE_ACK 419 and 421 to all ARS's that are associated with therelaying path (e.g. ARS 201 and ARS 203) to initiate relaying for thecall. ARS 201 and 203 consequently reserve RBW for the call. MH 113 isinstructed to initiate the call when BTS 109 (which functions as thehome BTS in the call) sends P_RELAY_ROUTE_ACK 423 to MH 113.

[0048]FIG. 5 shows apparatus of PSC 151 according to an embodiment ofthe invention. PSC 151 communicates with to BTS 107, 109, and 111through data port 503 over control lines 152, 154, and 156 (as shown inFIG. 2). Messages to and from BTS 107, 109, and 111 are processed byprocessor 501. In order to determine the shortest relaying path inresponse to receiving P_RELAY_REQ 413, processor 501 accesses datastructure 505 to obtain bandwidth information 509 (both the CBW's ofBTS's and the RBW's of ARS's) and accesses data structure 507 to obtaintopological information 511 (which reflects the connectivity among ARS'sand BTS's) for feasible relaying paths between the proxy ARS and thedestination BTS. In the embodiment, topological information 511 isupdated by the service provider inputting topological informationthrough data port 503 and processor 501.

[0049]FIG. 6 shows apparatus for ad hoc relaying station (ARS) 600according to an embodiment of the invention. The apparatus shown for ARS600 is the same as for ARS 201, 203, 205, 207, and 209 in theembodiment. ARS 600 utilizes R-interface 603 when communicating with anMH or another ARS and utilizes C-interface 605 when communicating with aBTS. Processor 601 processes messages from R-interface 603 andC-interface 605 as described in the signaling protocol scenarios ofFIGS. 4, 9, 10, 12, 13, and 15. Data structure 607 functions as aswitching table. Each entry corresponds to a call that is supported byARS 600. Entry MH_ID 609 corresponds to the identification of the MH(e.g. telephone number or IP address), entry 611 is the identificationof the next node in the relaying path (either an ARS or BTS), and entry613 is the previous node in the path (either the MH or an ARS).

[0050]FIG. 7 shows apparatus for mobile host (MH) 700 according to anembodiment of the invention. The apparatus shown for MH 700 is the sameas for MH 113 and for MH 115. MH 700 supports both R-interface 703 (whencommunicating with an ARS) and C-interface 705 (when communicating witha BTS). Processor 701 processes messages from R-interface 703 andC-interface 705 in accordance with the signaling protocol scenariosshown in FIGS. 4, 9, 10, 12, 13, and 15.

[0051]FIG. 8 shows apparatus of base transceiver station (BTS) 800according to an embodiment of the invention. The apparatus shown for BTS800 is the same as for BTS 101, 103, and 105 in the exemplaryembodiments. BTS 800 communicates with PSC 151 through data port 805.BTS 800 communicates with MH 113 and MH 115 through C-interface 803.Processor 801 processes messages from data port 805 and C-interface 803in accordance with the signaling protocol scenarios shown in FIGS. 4, 9,10, 12, 13, and 15.

[0052]FIG. 9 shows a PSC-assisted signaling protocol scenario utilizingsecondary relaying according to a variation of the first embodiment. Thesignal protocol scenario of FIG. 9 corresponds to the architecture thatis shown in FIG. 3. In the embodiment, secondary relaying is attemptedif primary relaying is successful. One reason for primary relay beingunsuccessful is that MH113 is not in close proximity to an ARS.Secondary relaying is then invoked so that an MH that is currentlyassigned CBW by the home BTS (BTS 109) is redirected to an ARS in closeproximity (proxy ARS) and a relaying path is established to a foreignBTS. In other embodiments of the invention, secondary relaying may beattempted without attempting primary relaying.

[0053] In FIG. 9, MH 113 initiates secondary relaying by sendingS_RELAY_REQ 901, which contains a sequence number in order to identifyMH 113, to BTS 109. BTS 109 multicasts the message by sendingS_RELAY_REQ 903 to all mobile hosts (e.g. MH 115) that have beenassigned CBW by BTS 109. In a variation of the embodiment, BTS 109multicasts message 903 only to mobile hosts in a group that areassociated with a level of quality of service (QoS). This variationenables mobile hosts to be grouped by a QoS level, in which only mobilehosts in the group are solicited for secondary relaying. (In a wirelesssystem, there is a probability that the a redirected mobile host mayencounter a degradation of service.) With the variation, mobile hosts inanother group that are associated with a different level of QoS are notsolicited for secondary relaying. With another variation of theinvention, S_RELAY_REQ 903 may be sent to mobile hosts with theR-interface if the mobile hosts are not equipped with both theC-interface and the R-interface.

[0054] When MH 115 (currently assigned CBW) receives message 903, MH 115multicasts S_RELAY_REQ 905 to all neighboring ARS's (e.g. ARS 207). ARS207 processes the first S_RELAY_REQ 905 containing the sequence number(corresponding to MH 113), ARS 207 sends S_RELAY_REQ 907 to BTS 109. Aplurality of ARS's can respond with message 907 having the same sequencenumber. Consequently, BTS 109 forwards S_RELAY_REQ 909 containing theresponses from ARS 207 and all other responding ARS's. PSC 151determines the shortest path from MH 115 to BTS 111 (which is consideredthe F_BTS), as with the scenario in FIG. 4. The shortest path (MH 115 toARS 207 to ARS 209 to BTS 111 as shown in FIG. 3) is associated with oneof the mobile hosts (e.g. MH 115) that is assigned CBW by BTS 109. InFIG. 9, the shortest path corresponds to MH 115. PSC 151 sendsS_RELAY_ACK 911 to BTS 109 and S_RELAY_ACK 913 to BTS 111 with therouting information for the shortest path (between MH 115 and BTS 111)and an identification of MH 115. BTS 109 and BTS 111 consequentlymulticasts S_RELAY_ACK 915 to ARS 207 and S_RELAY_ACK 917 to ARS 209 inorder to reserve bandwidth for the relaying path. MH 115 is instructedto connect to the relaying path by BTS 109 sending S_RELAY_ACK 919 to MH115. MH 115 relinquishes its C-link, and MH 113 is assigned CBW when MH113 receives S_RELAY_ACK 921.

[0055]FIG. 10 shows a link-state based distributed signaling protocolscenario utilizing primary relaying according to a second embodiment ofthe invention. The signaling protocol scenario of FIG. 10 corresponds tothe architecture that is shown in FIG. 2. With the link-state baseddistributed signaling protocol, each ARS maintains information about theiCAR's topology and maintains bandwidth information about other ARS's.(In the embodiment, an ARS exchanges bandwidth information bybroadcasting bandwidth information about itself and its neighboringARS's over the R interface.) With PSC-based signaling (FIGS. 4 and 9),PSC 151 maintains this information.

[0056] MH 113 requests for a call by sending CBW_REQ 1001 to BTS 109.BTS 109 consequently queries PSC 151 whether sufficient CBW is availableat BTS 109 by sending CBW_REQ 1003 to PSC 151. (In the embodiment, BTS109 does not maintain bandwidth information in order to reduce thecomplexity of BTS 109. However, with an alternative embodiment BTS 109may maintain bandwidth information.) In the example, there is notsufficient CBW, and PSC 151 returns CBW_INFO 1005 to BTS 109. Message1005 contains a list of candidate destination BTS's with the associatedavailable CBW. BTS 109 forwards this information by sending CBW_INFO1007 to MH 113. When MH 113 receives message 1007 (signifying that MHneeds to initiate primary relaying), MH 113 multicasts R_RELAY_REQ 1009to neighboring ARS's (e.g. ARS 201). Each ARS that receives message 1009determines a minimum cost (e.g. number of hops or available bandwidth)and responds with ARS_ACK 1011 with the minimum cost. MH 113 sendsP_RELAY_ORD 1013 to the ARS responding with the lowest cost function(e.g. ARS 201). Upon receiving message 1013, ARS 201 initiates theconnection on a hop-hop basis to the destination BTS (e.g. 107) bysending ARS 203 P_RELAY_REQ 1015. Message 1015 contains an indicationthat a relaying path should be established and may contain the routinginformation for the relaying path. ARS 203 sends P_RELAY_REQ 1017 to thenext node, which is BTS 107 in the example. BTS 107 determines whethersufficient CBW is available by sending CBW_REQ 1019 to PSC 151 andreceiving CBW_AL 1021 from PSC 151. (BTS 107 queries PSC 151 aboutavailable CBW because information about the available CBW that iscontained message 1005 may not be current.) Consequently. BTS 107responds with P_RELAY_ACK 1023, causing ARS 203 to respond withP_RELAY_ACK 1025 to ARS 201. ARS 201 sends P_RELAY_ACK 1027 to MH 113 toindicate that the relaying path has been established.

[0057]FIG. 11 shows apparatus of an ad hoc relaying station (ARS) 1100that supports the protocol scenarios shown in FIGS. 10 and 12. Processor1101, data structure 1107, R-interface 1103, and C-interface 1105correspond to data structure 607, R-interface 603, and C-interface 605in FIG. 6. ARS 1100 contains data structures 1119 and 1121 in order thatARS 1100 can determine the shortest relaying path when ARS 1100 receivesP_REQ_REQ (e.g. message 1009) with a link-based distributed signalingprotocol.

[0058]FIG. 12 shows a link-state based distributed signaling protocolscenario utilizing secondary relaying according to a variation of thesecond embodiment of the invention. The signaling protocol scenario ofFIG. 12 corresponds to the architecture that is shown in FIG. 3. In theembodiment, MH 113 sends S_RELAY_REQ 1201 to BTS 109. BTS 109 multicastsS_RELAY_REQ 1203 to mobile hosts that are currently assigned CBW (i.e.,active mobile hosts). Message 1203 also contains information aboutcandidate BTS's that have available CBW. In the embodiment, BTS 109stored the CBW information that was contained in message 1203 when MH113 attempted primary relaying. However, alternative embodiments canquery PSC 115 for CBW information as in FIG. 10. Consequently, activemobile hosts (e.g. MH 113) multicasts S_RELAY_REQ 1205 to neighboringARS's (e.g. ARS 207). Responding ARS's (e.g. ARS 207) return ARS_ACKwith the best path information to the candidate BTS's. MH 115 returnsthis information to BTS 109 with the best path information BTS 109determines the best path spanning the active mobile hosts. In theembodiment, BTS 109 chooses the path corresponding to a smallest numberof hops. In FIG. 12, the best path corresponds to MH 115; thus, BTS 109sends S_RELAY_ORD 1211 to MH 115. MH 115 initiates the establishment ofthe relaying path by sending S_RELAY_ORD 1213 to ARS 207. BTS 109 sendsa message to each of the remaining active mobile hosts in order tocancel any further action. The establishment of the relaying path issimilar as with FIG. 10 corresponding with messages 1215, 1217, 1219,1221, and 1223. With the establishment of the relaying path, ARS 207returns S_RELAY_ACK 1225 to MH 115 to redirect the call through therelaying path. The CBW is reassigned to MH 113 by MH 115 sendingCBW_RELEASE 1227 to BTS 109, and S_RELAY_ACK 1229 is consequently sentto MH 113.

[0059]FIG. 13 shows a distributed signaling protocol scenario utilizingprimary relaying in accordance to a third embodiment of the invention.The signaling protocol scenario corresponds to the architecture that isshown in FIG. 2. The distributed signaling protocol scenarios that areshown in FIGS. 13 and 15 differ from the link-state based distributedsignaling protocol scenarios that are shown in FIGS. 10 and 12 becauseARS's do not maintain bandwidth information with distributed signaling.

[0060] MH 113 requests a call by sending CBW_REQ 1301 to BTS 109. Aswith FIG. 10 (link-state based distributed signaling utilizing primarysignaling), BTS 109 sends CBW_REQ 1303 to PSC 151 in order to determinewhether sufficient CBW is available to serve the call. PSC 151 returnsCBW_REQ 1305 to BTS 109, indicating that there is not sufficient CBW.Message 1305 contains a list of candidate destination BTS's (which areforeign BTS's) with associated available CBW. BTS 109 forwards theinformation to MH 113 by sending CBW_INFO 1307. Consequently, MH 113multicasts P_RELAY_REQ 1309 with the list of candidate BTS's and theassociated CBW to neighboring ARS's (e.g. ARS 201).

[0061] When ARS 201 receives message 1309, ARS 201 accesses its routingtable (data structure 1415 as described in FIG. 14) in order todetermine if any of the destination BTS's is reachable. If so, ARS 201returns ARS_ACK 1311. Because ARS's do not have bandwidth information ofother ARS's, each ARS receiving message 1309 may attempt to establish arelaying path to a destination BTS in order to achieve a highprobability of successfully establishing a relaying path. (Withlink-state base distributed signaling, only one ARS establishes arelaying path.) The establishment of a relaying path in FIG. 13(messages 1313, 1315, 1317, 1319, 1321, and 1323) is similar to thelink-state based distributed signaling protocol shown in FIGS. 10 and12.

[0062] When ARS 201 has successfully established the relaying path, ARS201 returns P_RELAY_ACK 1325 to MH 113. Because MH 113 can receive aplurality of responses, MH 113 selects the first response from theARS's. In FIG. 13, the first responding ARS is ARS 201. MH 113establishes the call through the relaying path that is provided by ARS201. Also, MH 113 sends a message to the remaining ARS's that haveresponded in order to tear down the corresponding relaying paths.

[0063]FIG. 14 shows apparatus of ad hoc relaying station (ARS) 1400 thatsupports the signaling protocol scenarios in FIGS. 13 and 15. Theapparatus shown for ARS 1400 is utilized by ARS 201, 203, 205, 207, and209 in the embodiment. Processor 1401 corresponds to processor 601 and1102; R-interface 1103 corresponds to R-interface 603 and 1103,C-interface 1405 corresponds to C-interface 1105 and 605; and datastructure 1407 corresponds to data structures 607 and 1107. Datastructure 1407 functions as a switching table for establishing arelaying path (corresponding to messages 1313, 1315, 1321, and 1323 inFIG. 13) in response to receiving a message to initiate theestablishment of a relaying path (P_RELAY_REQ 1309 in FIG. 13). Datastructure 1415 is indexed by an identification of a destination BTS.When ARS 201 receives R_RELAY_REQ 1309, which contains a list ofdestination BTS's, ARS 201 retrieves next hop entry 1417 and number ofhops entry 1419 that is associated with a candidate BTS. In theembodiment, ARS 1400 attempts to establish a relaying path having thesmallest number of hops (corresponding to entry 1419).

[0064]FIG. 15 shows a distributed signaling protocol scenario utilizingsecondary relaying according to a variation of the third embodiment ofthe invention. The signaling protocol scenario corresponds to thearchitecture that is shown in FIG. 3. In the embodiment, secondaryrelaying is attempted after primary relaying was unsuccessful. However,other embodiments may utilize secondary relaying without attemptingprimary relaying. MH 113 initiates secondary relaying by sendingS_RELAY_REQ 1501 to BTS 109. In the embodiment, BTS 109 has informationabout the candidate list and associated available CBW from the previousattempt for primary relaying (i.e. message 1305 as shown in FIG. 13).(However, with an alternative embodiment, BTS 109 may query PSC 151 ifprimary relaying is not attempted before secondary relaying.) BTS 109includes this information in S_RELAY_REQ 1503 that is sent to all activemobile hosts (e.g., MH 115). Each active mobile host multicastsS_RELAY_REQ 1505 to neighboring ARS's (e.g. ARS 207). ARS 207 respondswith ARS_REQ 1507 if any of the candidate BTS's (that is contained in alist of candidates in S_RELAY_REQ 1505) is reachable. ARS 207 attemptsto establish a relaying path to a candidate BTS (corresponding to BTS111). The associated messages are 1509, 1511 1513, 1515, 1517, and 1519and corresponds to messages 1313, 1315, 1317, 1319, 1321, and 1323 inFIG. 13.

[0065] When an ARS has successfully established a relaying path, the ARS(e.g. ARS 207) returns S_RELAY_ACK 1521 to the requesting mobile host(e.g. MH 115). MH 115 selects the ARS that responds first (correspondingto ARS 207). MH 115 sends MH_ACK 1523 to BTS 109. Because a plurality ofmobile hosts can respond with a MH_ACK message, BTS 109 selects theactive mobile host that responds first. In FIG. 15, the first mobilehost that responds is MH 115; thus BTS 109 sends S_RELAY_ORD 1525 to MH115. Consequently, MH 115 redirects its current call through therelaying path established by ARS 207. BTS 109 instructs all other activemobile hosts to cancel any further action; consequently, a message totear down relaying paths for the associated ARS's is multicasted.

[0066] As can be appreciated by one skilled in the art, a computersystem with an associated computer-readable medium containinginstructions for controlling the computer system can be utilized toimplement the exemplary embodiments that are disclosed herein. Thecomputer system may include at least one computer such as amicroprocessor, digital signal processor, and associated peripheralelectronic circuitry.

[0067] While the invention has been described with respect to specificexamples including presently preferred modes of carrying out theinvention, those skilled in the art will appreciate that there arenumerous variations and permutations of the above described systems andtechniques that fall within the spirit and scope of the invention as setforth in the appended claims.

I/we claim:
 1. A method for supporting a call for a wireless terminal inan integrated cellular and ad-hoc relaying (iCAR) system, the iCARcomprising a wireless controller, the method comprising the steps of:(a) determining that a first base transceiver station (BTS) does nothave a channel to support the call, the first BTS utilizing a firstfrequency spectrum; (b) receiving a request to initiate a relaying pathfor the wireless terminal in response to step (a); (c) determining therelaying path that utilizes at least one relaying station and a secondBTS in response to step (b), the at least one relaying station utilizinga second frequency spectrum; and (d) sending an instruction to the firstBTS and to the second BTS in order to initiate an establishment of therelaying path in response to step (c).
 2. The method of claim 1, whereinstep (c) comprises the step of minimizing a cost to determine therelaying path.
 3. The method of claim 2, wherein the cost corresponds toa number of relaying stations that are configured for the relaying path.4. The method of claim 1, wherein step (c) comprises the steps of: (i)determining an available bandwidth for each of the at least one relayingstations and for the second BTS; (ii) calculating a reciprocal of theavailable bandwidth for the each of the at least one relay stations andthe second BTS; (iii) summing the reciprocals; and (iv) selecting therelaying path that corresponds to a minimum sum of the reciprocals. 5.The method of claim 5, further comprising the step of: maintainingbandwidth and topological information about the iCAR system.
 6. A methodfor supporting a call for a wireless terminal in an integrated cellularand ad-hoc relaying (iCAR) system, the iCAR system comprising a relayingstation, the method comprising the steps of: (a) receiving a relayingrequest about supporting a relaying path; (b) sending a first messagethat indicates a status about supporting the relaying path in responseto step (a); and (c) establishing the relaying path to a next node inthe relaying path, wherein the next node is selected from the groupconsisting of a second relaying station and a base transceiver station(BTS).
 7. The method of claim 6, wherein the first message is sent to awireless controller.
 8. The method of claim 6, wherein the first messageis sent to a mobile host.
 9. The method of claim of claim 6, furthercomprising the step of: (d) sending a second message that indicates thatthe relaying path has been successfully established, in response to step(c).
 10. The method of claim 6, further comprising the step of: (d)receiving a second message in response to step (b), and wherein step (c)is responsive to step (d).
 11. The method of claim 6, further comprisingthe step of: (d) determining a cost that is associated with the relayingpath, wherein the cost is contained in the first message.
 12. The methodof claim 11, further comprising the step of: (e) maintaining bandwidthinformation and topological information about other relaying stations,wherein step (d) is responsive to step (e).
 13. A method for supportinga call for a wireless terminal in an integrated cellular and ad-hocrelaying (iCAR) system, the method comprising the steps of: (a)receiving a message in response to a condition that a base transceiverstation has inadequate resources to support additional calls; (b)requesting at least one relaying station about an establishment of arelaying path; (c) determining whether to establish the call with one ofthe at least one relaying stations; and (d) establishing the callthrough the one of the at least one relaying station.
 14. The method ofclaim 13, wherein step (c) comprises the step of: selecting the one ofthe at least one relaying stations corresponding to a minimum cost. 15.The method of claim 14, wherein the cost corresponds to a number ofrelaying stations that are configured for the relaying path.
 16. Themethod of claim 13, wherein step (c) comprises the step of: selectingthe one of the at least one relaying stations that responds before otherrelaying stations.
 17. The method of claim 13, wherein step (c)comprises the step of: receiving a command to establish the call. 18.The method of claim 13, further comprising the steps of: utilizing aresource of the base transceiver station to support the call before step(a), the resource associated with a first frequency spectrum; andutilizing a second resource of a relaying station to support the call inresponse to step (d), the second resource associated with a secondfrequency spectrum.
 19. The method for a first wireless terminalsupporting a call in an integrated cellular and ad-hoc relaying system,the method comprising the steps of: (a) requesting a channel that isassigned to a base transceiver station in order to support a call; (b)receiving a response that the base transceiver station does not have aresource to support the call; (c) requesting for a relaying path tosupport the call in response to step (b); (d) receiving a secondresponse that the relaying path cannot be established; and (e)requesting that a second wireless terminal be assigned to a secondrelaying path, wherein a second resource that was assigned to the secondterminal is reassigned to the first wireless terminal, and wherein thesecond resource is associated with the base transceiver station.
 20. Amethod for supporting a call for a wireless terminal in an integratedcellular and ad-hoc relaying (iCAR) system, the iCAR system comprising abase transceiver station (BTS), the method comprising the steps of: (a)determining that a resource is not available in response to a request tosupport a call, the resource associated with a first frequency spectrum;and (b) sending a message to initiate a procedure for an establishmentof a relaying path for the wireless terminal, the relaying pathassociated with a second frequency spectrum.
 21. The method of claim 20,further comprising the steps of: (c) receiving a second message fromeach of a plurality of relaying stations, the second message containingan associated cost that characterizes an associated relaying path, inresponse to step (b); (d) selecting the relaying path from a pluralityof possible relaying paths according to one of the plurality of possiblerelaying paths that has a minimum associated cost; and (e) instructingthe wireless terminal to utilize the one relaying path.
 22. The methodof claim 20, further comprising the steps of: (c) receiving a secondmessage from each of a plurality of relaying stations; (d) selecting therelaying path from a plurality of possible relaying paths according toone of the plurality of relaying stations that responded before otherrelaying stations; and (e) instructing the wireless terminal to utilizethe relaying path.
 23. A wireless controller for supporting a call for awireless terminal in an integrated cellular and ad-hoc relaying (iCAR)system, the wireless controller comprising: a data port; a processorcommunicating with a plurality of base transceiver stations through thedata port, the processor configured to perform the steps of: (a)determining that a first base transceiver station (BTS) does not have achannel to support the call; (b) receiving a request to initiate arelaying path for the wireless terminal; and (c) sending an instructionto the first BTS and to the second BTS in order to establish therelaying path.
 24. The wireless controller of claim 23, wherein theprocessor is configured to perform the further step of: (d) determiningthe relaying path that configures at least one relaying station to asecond BTS.
 25. The wireless controller of claim 23, further comprising:a data structure comprising bandwidth and topological information aboutthe iCAR system, wherein the processor is configured to perform step (c)by minimizing a cost to determine the relaying path utilizing thebandwidth and topological information.
 26. A computer-readable mediumcontaining instructions for controlling a computer system to support acall for a wireless terminal in an integrated cellular and ad-hocrelaying (iCAR) system, the iCAR system comprising a wirelesscontroller, the computer-readable medium comprising instructions thatperform the steps of: (a) determining that a first base transceiverstation (BTS) does not have a channel to support the call; (b) receivinga request to initiate a relaying path for the wireless terminal; and (c)sending an instruction to the first BTS and to the second BTS in orderto initiate an establishment of the relaying path.
 27. Thecomputer-readable medium of claim 26, further comprising the step of:(d) determining the relaying path that configures at least one relayingstation to a second BTS.
 28. A relaying station for supporting a callfor a wireless terminal in an integrated cellular and ad-hoc relaying(iCAR) system, the first relaying station comprising: a C-interface thatutilizes a first frequency spectrum; an R-interface that utilizes asecond frequency spectrum; a processor communicating with a secondrelaying station and a wireless terminal through the R-interface andcommunicating with a base transceiver station through the C-interface,the processor configured to perform the steps of: (a) receiving arelaying request about supporting a relaying path; (b) sending a firstmessage that indicates a status about supporting the relaying path inresponse to step (a); and (c) establishing the relaying path to a nextnode in the relaying path, wherein the next node is selected from thegroup consisting of the second relaying station and a base transceiverstation (BTS).
 29. The relaying station of claim 28, further comprising;a data structure comprising bandwidth and topological information aboutthe iCAR system, wherein the processor is configured to perform thefurther step of determining a cost for the relaying path utilizing thebandwidth and topological information.
 30. A computer-readable mediumcontaining instructions for controlling a computer system to support acall for a wireless terminal in an integrated cellular and ad-hocrelaying (iCAR) system, the iCAR system comprising a relaying station,the computer-readable medium comprising instructions that perform thesteps of: (a) receiving a relaying request about an utilization of therelaying station, wherein the utilization corresponds to supporting arelaying path; (b) sending a first message that indicates a status aboutthe utilization of the relaying station in response to step (a); and (c)establishing the relaying path to a next node in the relaying path,wherein the next node is selected from the group consisting of a secondrelaying station and a base transceiver station (BTS).
 31. A wirelessterminal for supporting a call in an integrated cellular and ad-hocrelaying (iCAR) system, the wireless terminal comprising: a C-interfacethat utilizes a first frequency spectrum; an R-interface that utilizes asecond frequency spectrum; a processor that communicates through theC-interface with a base transceiver station and communicates through theR-interface with a relaying station, the processor configured to performthe steps of: (a) receiving a message in response to a condition that abase transceiver station has inadequate resources to support additionalcalls; (b) requesting at least one relaying station about anestablishment of a relaying path; (c) determining whether to establishthe call with one of the at least one relaying stations; and (d)establishing the call through the one of the at least one relayingstation.
 32. A computer-readable medium containing instructions forcontrolling a computer system to support a call for a wireless terminalin an integrated cellular and ad-hoc relaying (iCAR) system, the iCARsystem comprising a relaying station, the computer-readable mediumcomprising instructions that perform the steps of: (a) receiving amessage in response to a condition that a base transceiver station hasinadequate resources to support additional calls; (b) requesting atleast one relaying station about an establishment of a relaying path;(c) determining to establish the call with one of the at least onerelaying stations; and (d) establishing the call through the one of theat least one relaying station.
 33. A base transceiver station forsupporting a call for a wireless terminal in an integrated cellular andad-hoc relaying (iCAR) system, the base transceiver station comprising:a C-interface that utilizes a first frequency spectrum; a processor thatcommunicates to the wireless terminal through the C-interface, theprocessor configured to perform the steps of: (a) determining that aresource is not available in response to a request to support a call,the resource associated with the first frequency spectrum; and (b)sending a message to initiate a procedure for an establishment of arelaying path for the wireless terminal, the relaying path utilizing asecond frequency spectrum.
 34. A computer-readable medium containinginstructions for controlling a computer system to support a call for awireless terminal in an integrated cellular and ad-hoc relaying (iCAR)system, the iCAR system comprising a base transceiver station, thecomputer-readable medium comprising instructions that perform the stepsof: (a) determining that a resource is not available in response to arequest to support a call, the resource associated with the firstfrequency spectrum; and (b) sending a message to initiate a procedurefor an establishment of a relaying path for the wireless terminal, therelaying path associated with a second frequency spectrum
 35. A methodfor supporting a call for a wireless terminal in an integrated cellularand ad-hoc relaying (iCAR) system, the iCAR system comprising a relayingstation, the method comprising the steps of: (a) receiving a request fora relaying path; (b) sending a response message to a base transceiverstation, the response message indicating that the relaying stationreceived the request; (c) receiving a command to establish a relayingpath to a next node, wherein the next node is selected from the groupconsisting of a second relaying station and second base transceiverstation; and (d) establishing the relaying path to the next node,wherein a first frequency spectrum is utilized if the next nodecorresponds to the second base transceiver station, and wherein secondfrequency spectrum is utilized if the next node corresponds to thesecond relaying station.
 36. A method for supporting a call for awireless terminal in an integrated cellular and ad-hoc relaying (iCAR)system, the method comprising the steps of: (a) requesting for a channelto support the call, the channel associated with a base transceiverstation and associated with a first frequency spectrum; (b) receiving amessage that indicates that the base transceiver station cannot providethe channel; (c) broadcasting a second message on a second frequencyspectrum, wherein the second message requests that a relaying stationrespond to the base transceiver station; (d) receiving a command toestablish the relaying path to the relaying station; and (e)establishing communications over the relaying path to the relayingstation, wherein the relaying path utilizes the second frequencyspectrum.
 37. A method for supporting a call for a wireless terminal inan integrated cellular and ad-hoc relaying (iCAR) system, the iCARsystem comprising a relaying station, the method comprising the stepsof: (a) maintaining bandwidth information and topological informationabout other relaying stations and base transceiver stations; (b)receiving a request about an establishment of a relaying path, therequest containing a list of candidate base transceiver stations,wherein one of the candidate base transceiver stations being included inthe relaying path; (c) determining the relaying path having a minimumcost utilizing the list of candidate base transceiver stations,utilizing the bandwidth information and the topological information; (d)sending a message with the minimum cost in response to step (c); (e)receiving an order to establish the relaying path in response to step(d); (f) establishing the relaying path to the one of the candidate basetransceiver stations in response to step (e); and (g) sending a secondmessage in response to step (f).
 38. A method for supporting a call fora wireless terminal in an integrated cellular and ad-hoc relaying (iCAR)system, the method comprising the steps of: (a) requesting for a channelto support the call, the channel associated with a base transceiverstation and associated with a first frequency spectrum; (b) receiving amessage that indicates that the base transceiver station cannot providethe channel; (c) broadcasting a second message on a second frequencyspectrum, wherein the second message requests that a relaying stationrespond to the base transceiver station; (d) receiving a response fromthe relaying station with a cost that is associated with the relayingpath that the relaying station can support; (e) determining whether thecost is less than an other cost provided by other relaying stations; (f)ordering the relaying station to establish the relaying path in responseto step (e); and (g) establishing communications on the relaying pathwith the relaying station, wherein the relaying path utilizes the secondfrequency spectrum.